(navigation image)
Home American Libraries | Canadian Libraries | Universal Library | Community Texts | Project Gutenberg | Children's Library | Biodiversity Heritage Library | Additional Collections
Search: Advanced Search
Anonymous User (login or join us)
Upload
See other formats

Full text of "Treatise On Applied Analytical Chemistry(Vol-1)"

437

refractivity and ratio value (see above) and from diminution in the acid
number (see later).

10.  Test for Japan Wax   (from various species of Rhus), Tallow
and other Fats in general.—A scrap of fused potassium bisulphate is
added to about i gram of the molten wax in a test-tube and the mixture
strongly heated over a direct flame : the pure wax gives pungent sulphurous
fumes, whereas in presence of fats (glycerides) the characteristic irritating
odour of acrolein (due to decomposition of the glycerine) is observed and
a strip of filter-paper, soaked in a solution of sodium nitroprusside and
a little piperidine and placed at the mouth of the tube, turns violet-
blue.

If this test shows the presence of glycerides, the glycerine is determined
as in General Methods, 17 ; the amount of glycerine, multiplied by 10, gives
approximately the quantity of fatty substance in the wax, since fats contain
on the average about 10% of glycerine.

It should also be borne in mind that Japan wax, tallow and other fats
lower the melting point and raise the saponification number (tallow raises
also the iodine number) of the wax (see later).

11.  Detection of Wool-Fat and its Products (Wool-Fat Stearine
or Wax).—The higher alcohols and hydrocarbons are extracted from the
wax by Leys' method (8), the mixture thus extracted being tested for
cholesterol by means of chloroform and sulphuric acid (see General Methods,
19, Higher Alcohols).

12.  Determination of the Water and Various Extraneous Im-
purities.—About 5 grams of the wax as it stands are heated at 100-105°
to constant weight, the loss representing the water.   The residue is dis-
solved in hot benzene and the solution filtered from any appreciable undis-
solved portion through a tared filter, the insoluble matter being washed
well with hot benzene, dried at 100° and weighed.

The residue insoluble in benzene is then tested for starchy or mineral
matters by the usual methods.

13.  Extraneous Colouring Matters.—About a gram of the rasped
wax is shaken with ammonia :   in presence of turmeric, a reddish-brown
coloration is obtained.

. To detect coal-tar dyes, the wax is extracted with 90-95% alcohol in
the hot. The liquid is then cooled well at 15° for some hours and filtered,
the filtrate being evaporated and tested for artificial colouring matters (see
Coal-tar Dyes in Vol. II). As a rule imitation wax and wax substitutes
are coloured with the so-called Soudan dyes, which are turned pink with
cone, hydrochloric acid.

14.  Detection of Beeswax in Mixtures with other Substances —
To ascertain if wax is contained in wares of different kinds, such as paraffin
wax, fats, candles, artificial fruit and flowers, lithographic stones, mastics,
encaustics, ointments, plasters, waxed paper and cloth, myricyl alcohol is
tested for.    This may be done indirectly by means of the acetyl number,
or by transforming the alcohol into melissic acid.   The test is, however,
practicable only when other substances containing higher alcohols, such as
wool-fat and its products, are excluded.   Carnauba wax, which also con-

• i '

t it may